The subject matter disclosed herein relates to propellers. More specifically, the subject disclosure relates to blade retention systems for propellers.
Modern aircraft propellers use composite materials to produce lightweight blades capable of supporting certain operating loads. These operating loads can include a centrifugal force component which acts in a direction parallel to the longitudinal axis of the propeller blade. Historically, retention systems of non-preloaded propeller blades rely on the centrifugal load generated by the weight of the blade structure during operation to stiffen the blade retention system for load carrying capability, especially the steady and cyclic bending loads. As propeller blades have gotten lighter with the use of composite materials, the retention systems of non-preloaded propeller blades have been altered to provide the necessary load for stiffening of the blade retention. This alteration has resulted in large and heavy parts for retention mechanisms.
Many propeller blade retention systems address the problems associated with size and result in weight reduction. These systems use an assembly of bearings for retention of the propeller blade inside a hub assembly. Such a bearing arrangement retains the propeller blade from inside the hub and provides appropriate blade retention stiffness to reduce the amount of vibration.
However, this design does not provide means for preloading which is required by retention systems that include modern composite blades. Such arrangements which are known do not provide ease of replacement and maintenance of parts.